Cameron rejected an invitation to join 26 European partners in a tighter financial alliance to save the euro which he said didn't adequately protect Britain's national interest and meant giving up too much control over regulation of Britain's dominant financial sector.

The move isolated Cameron from the European Union and raised doubts about whether Britain realistically can remain a member of the 27-nation bloc — prompting cheers from the prime minister's typically anti-EU party and jeers from the opposition.

Treasury chief George Osborne defended Cameron on BBC radio, saying he thinks Britons are pleased the prime minister "stood up for the British national interest.

"We have protected Britain's financial services and manufacturing companies that need to be able to trade their products into Europe from the development of eurozone integration spilling over and affecting non-euro members of the EU," he said.

Osborne added that if the prime minister had "caved in" to signing the treaty, the "full force" of the EU could have undermined British interests.

"We were not prepared to let that happen," he said.

Osborne's vote of confidence echoed support from other Conservative lawmakers over the prime minister's move to set Britain apart.

But Cameron also is facing a chorus of criticism from the opposition Labour Party and growing tensions with his Conservative Party's junior coalition partner, the Liberal Democrats.

Deputy Prime Minister Nick Clegg has rejected talk of a rift between his Liberal Democrats and the Conservatives and backed Cameron's move, but dissent bubbled up from elsewhere in the party.

One Liberal Democrat lawmaker accused Cameron of "betraying Britain," while another called the fallout "a black day for Britain and Europe."

In Italy, Premier Mario Monti has summoned union leaders to discuss his new austerity plan as lawmakers tinker with his tough proposals to try to rescue the country from its debt load and get the economy growing again.

Unions have bitterly contested Monti's proposal to reform Italy's generous pension system and have called a strike for Monday. Monti's office said Saturday the premier, fresh from the EU summit in Brussels, would meet with union leaders on Sunday to discuss the proposals.

Monti has also proposed restoring a property tax suspended during Premier Silvio Berlusconi's government. The proposal has renewed criticism of the tax-exempt status of the Catholic Church in Italy, even though the church merely enjoys the same tax-exempt status as any non-profit.